Various synthetic fluids, including synthetic hydrocarbons and silahydrocarbons, which are stable at high temperatures, have been developed which are useful in the formulation of hydraulic fluids and lubricants, among other uses. Multiple substituted silanes, and in particular tetrasubstituted-silanes, have been proposed for the use in the formulation of hydraulic fluids and lubricants since they possess excellent viscosities, low pour points, and excellent thermal stability over a wide temperature range.
Various methods for the synthesis of tetraalkyl-substituted silanes possessing desired properties involve the addition of a Grignard reagent or alkyllithium compounds to alkyltrichlorosilanes, such as shown in U.S. Pat. No. 4,367,343. Other methods of making silahydrocarbons from alkylchlorosilanes are reported, such as in U.S. Pat. No. 4,595,777, in which an alkylchlorosilane having the formula R.sub.x SiCl.sub.(4-x), wherein R is an alkyl radical, and a trialkylaluminum compound having the formula AlR.sub.1 R.sub.2 R.sub.3, wherein R.sub.1-3 are the same or different alkyl radicals, produce a desired tetraalkylsilane product having the general formula RSiR.sub.1 R.sub.2 R.sub.3. However, nothing is taught as to the control of particular proportions of the possible various different reaction product.
U.S. Pat. Nos. 4,572,791 and 4,578,497 teach the preparation of silahydrocarbons including dialkylsilanes having the formula SiH.sub.2 R.sub.2 and trialkylsilanes having the formula RSiH(R.sub.1).sub.2 wherein R and R.sub.1 are alkyl radicals from 1 to 20 carbon atoms. However, such reactions were catalyzed reactions utilizing rhodium or platinum catalysts.
Because the properties of the silahydrocarbon depends in part upon the proportions of such product mixtures, such as proportions of dialkylsilanes to trialkylsilanes, then it would be advantageous to have methods which could effectively control the proportions of such product mixtures.